haifa memory abuse

[Richard Henderson]

Consider a function such as

	void foo()
	{
	  bar(1);
	  bar(2);
	  ...
	  bar(6000);
	}

At present, such a function will take about 1GB to compile.
This is due to haifa creating _exceedingly_ long dependancy
chains for the call_insns.

The problem was that we never zapped the reg_last_uses and
reg_last_sets lists, which meant that each call_insn depended
on every instruction before it.  Yikes.

This patch, bootstrapped on i686 and alphaev6, reduces peak
memory usage for the aforementioned function to 12MB.


r~


        * haifa-sched.c (sched_analyze_1): Don't special-case calls
        for clobbering registers.
        (sched_analyze_2): Likewise.
        (sched_analyze): Zap reg_last_uses and reg_last_sets after calls.

Index: haifa-sched.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/haifa-sched.c,v
retrieving revision 1.163
diff -c -p -d -r1.163 haifa-sched.c
*** haifa-sched.c	2000/11/14 09:58:40	1.163
--- haifa-sched.c	2000/11/22 19:18:44
*************** sched_analyze_1 (deps, x, insn)
*** 3384,3394 ****
  		}
  	      else
  		SET_REGNO_REG_SET (reg_pending_clobbers, r);
- 
- 	      /* Function calls clobber all call_used regs.  */
- 	      if (global_regs[r] || (code == SET && call_used_regs[r]))
- 		for (u = deps->last_function_call; u; u = XEXP (u, 1))
- 		  add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
  	    }
  	}
        else
--- 3384,3389 ----
*************** sched_analyze_2 (deps, x, insn)
*** 3540,3550 ****
  		/* ??? This should never happen.  */
  		for (u = deps->reg_last_clobbers[r]; u; u = XEXP (u, 1))
  		  add_dependence (insn, XEXP (u, 0), 0);
- 
- 		if (call_used_regs[r] || global_regs[r])
- 		  /* Function calls clobber all call_used regs.  */
- 		  for (u = deps->last_function_call; u; u = XEXP (u, 1))
- 		    add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
  	      }
  	  }
  	else
--- 3535,3540 ----
*************** sched_analyze (deps, head, tail)
*** 3987,3995 ****
  		  {
  		    for (u = deps->reg_last_uses[i]; u; u = XEXP (u, 1))
  		      add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
  
  		    for (u = deps->reg_last_sets[i]; u; u = XEXP (u, 1))
! 		      add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
  
  		    SET_REGNO_REG_SET (reg_pending_clobbers, i);
  		  }
--- 3977,3987 ----
  		  {
  		    for (u = deps->reg_last_uses[i]; u; u = XEXP (u, 1))
  		      add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
+  		    free_INSN_LIST_list (&deps->reg_last_uses[i]);
  
  		    for (u = deps->reg_last_sets[i]; u; u = XEXP (u, 1))
! 		      add_dependence (insn, XEXP (u, 0), REG_DEP_OUTPUT);
!  		    free_INSN_LIST_list (&deps->reg_last_sets[i]);
  
  		    SET_REGNO_REG_SET (reg_pending_clobbers, i);
  		  }